IEE works exactly this way, everything applies to every ally, but the conversion doesn't. And as I said before, conversion is restricted to user only. It would be really stupid (like actually dumb) if you played multiplayer with an elemental purifier and changed 90% of his damage to Acid because you want more damage. This would result in avoiding conversion builds in multiplayer, as one little aura would make other builds shit.

I am pretty sure you would not want to play with someone like that either. This is what Crate thought when implementing this.